Immobilization, stabilization, and activation of human stem cell factor (SCF) on fragmin/protamine microparticle (F/P MP)‐coated plates

Fragmin (low‐molecular‐weight heparin)/protamine microparticles (F/P MPs) immobilize to culture plates, thereby retaining the binding of heparin‐binding cytokines such as human stem cell factor (SCF). The purpose of this study was to evaluate the ability of F/P MP‐coating to immobilize, stabilize, and enhance SCF‐activity. Cell assays showed that SCF and preimmobilized SCF on F/P MP‐coated plates significantly stimulated the proliferation of human erythroleukemia cell line TF‐1 in a concentration‐dependent manner. Heparin and fragmin enhanced SCF‐induced proliferation of chlorate‐treated TF‐1 cells, in which the biosynthesis of endogenous sulfated polysaccharides was blocked, on noncoated plates at a range of concentrations (2–8 μg/mL). However, heparin and fragmin had no effect on SCF‐induced proliferation of chlorate‐treated TF‐1 cells on F/P MP‐coated plates. The interaction of SCF with fragmin and F/P MPs prolonged the half‐life of SCF bioactivity, and immobilized and protected SCF from inactivation, such as from heat and proteolysis. These results suggest that F/P MP‐coated plates protect SCF and enhance its activity, and F/P MP‐coating provides an excellent biomaterial to immobilize and retain heparin‐binding cytokines, including SCF, in bioactive form for optimal expansion of hematopoietic cells. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010